U.S. Pat. No. 4,655,530 A reveals a snap-in module for the frame of a receiver or a test adapter which is secured by means of a plunger, which is preloaded by a spring. A run-on bevel on the plunger ensures that the module snaps in automatically on insertion. To remove the module, the plunger is moved with a tool which can be screwed onto a thread of the plunger in order to release the module from the frame.
U.S. Pat. No. 3,040,289 A describes a similar solution, in which the modules are secured by a plunger which is preloaded with a spring, wherein the plunger/spring combination is in this case located on the receiver frame rather than on the module. A run-on bevel on the module ensures that the module snaps in automatically on insertion. To remove the module, the plunger has to be moved back against the spring force by means of a handle.
U.S. Pat. No. 6,547,587 B2 discloses a module with a fixed cam and a spring-loaded plunger. For insertion into a receiver frame, the module is fitted into the receiver frame from behind, wherein it is firstly placed with the cam into a corresponding slot in a rail on the bottom of the receiver frame, then tipped forwards and subsequently pushed upwards, in order there also to engage in a rail. In the process, the plunger is firstly pushed back from a front side of the upper rail against the spring force and, as soon as it has reached a hole through the upward movement of the module, is moved by the spring into the hole in order to secure the module. To remove the module, the plunger has to be moved back by means of a tool.
U.S. Pat. No. 5,562,458 A proposes fastening the modules to the frame with conventional bolts or screws. Likewise, U.S. Pat. No. 4,329,005 A refers merely to screws, which are intended to engage in slots.